7mm rem mag question

[Aussie Hunter Steve]

To see if the head is starting to seperate, look into your empty case with a strong light behind you, eg sunlight. You will see a groove starting to form at the start of the web area, the deeper the groove the closer you are to separation.

 

[archangel485]

That is interesting, looks like scratches at first glance but can't tell for sure. Many have said it already but seems your headspace may be off. Was a go/no-go gauge used to ensure your headspace is set right? Might be worth looking at in addition to checking your brass sizing. A comparator for headspace is definitely a good thing to have, however if you need something quick you can use something square on the ends that will fit over the neck of the brass that will touch the shoulder. I've used sockets for this purpose before, not quite as nice as a comparator designed for the case but if you need something asap without waiting for something in the mail that will help you know how much your die is bumping shoulders back.

 

[Sheephuntr]

That is interesting, looks like scratches at first glance but can't tell for sure. Many have said it already but seems your headspace may be off. Was a go/no-go gauge used to ensure your headspace is set right? Might be worth looking at in addition to checking your brass sizing. A comparator for headspace is definitely a good thing to have, however if you need something quick you can use something square on the ends that will fit over the neck of the brass that will touch the shoulder. I've used sockets for this purpose before, not quite as nice as a comparator designed for the case but if you need something asap without waiting for something in the mail that will help you know how much your die is bumping shoulders back.

It's a factory browning xbolt.

 

[codyadams]

Also to check for headcase separation, straiten a paper clip and bend the end at a 90° angle, and use it as a feeler down in the case. You will feel a divit or crack if it is impending.

 

[Sheephuntr]

Forgot to mention that this is only the third time these cases have been fired.

 

[jimbires]

I use a hornady headspace tool . here is a video that explains how to size brass without a tool . this is probably the most accurate way of doing this .

alex wheeler accuracy youtube videos - Search Videos

www.bing.com

 

[WalksLikeADeer]

Forgot to mention that this is only the third time these cases have been fired.

Also, check your trim length each time. Not trimming can cause over pressure and case head separation. I have seen this happen.

 

[David Emerson]

This is my first year reloading for a 7mag an I've got a question. Am I seeing case head separation??? The load is 66grains of RL26 behind a 168 Berger vld hunting. Winchester brass an federal 215 mag primers.

Hard to tell from your picture. Usually when heads are about to separate you will see a dark line. If you are wondering or not sure straighten out a bigger paper clip and put a short hook on the end and sharpen the tip of the hook. You can easily feel the thinner part where the head is pulling away from the body. Typically caused by sizing too much. If you do have one separate in the gun jam an empty 06 size case in to your gun. It will slide inside the mag case and you will be able to pull it out of your chamber.

 

[corsair4360]

If your cases are not showing signs of case head separation the chamber you have in your rifle may be large. The previous posts have good instructions on how to check for case head separation.

I had a 7mm Rem Mag rifle chamber that was so large the case belt could not have been working, sold that rifle many years ago.

 

[bigbull]

Many have said it already but seems your headspace may be off. Was a go/no-go gauge used to ensure your headspace is set right?

Guys Guys, please. This is very wrong information.
Measuring head space on a belted case does nothing for the issue being discussed.

The head space guages for belted cases have no bearing on the shoulder location or on being able to help with case separation preventative measurements.
Measuring Head space on a case which head spaces on the shoulder has merit but not for belted cases where the guage measures only the belt location in reference to the bolt face location, the shoulder location can float all over the place depending on how much you bump the shoulder back and this alone will contribute to the separation.

The only solution to lengthening the life of the brass is to head space off the shoulder but in order to do this..........first shot preparation is critical, the case has to be tight against the bolt face prior to firing that first shot, then sized minimally in order not to create too much head space for future case reloading life.

 

[archangel485]

Guys Guys, please. This is very wrong information.
Measuring head space on a belted case does nothing for the issue being discussed.

The head space guages for belted cases have no bearing on the shoulder location or on being able to help with case separation preventative measurements.
Measuring Head space on a case which head spaces on the shoulder has merit but not for belted cases where the guage measures only the belt location in reference to the bolt face location, the shoulder location can float all over the place depending on how much you bump the shoulder back and this alone will contribute to the separation.

The only solution to lengthening the life of the brass is to head space off the shoulder but in order to do this..........first shot preparation is critical, the case has to be tight against the bolt face prior to firing that first shot, then sized minimally in order not to create too much head space for future case reloading life.

What specifically is very wrong information? I'm a little confused by what you're saying. Are you saying if you buy a headspace gauge for a 7mm Rem mag it won't actually give you the headspace measurement because the belt is somehow in the way? Like your gauge will touch the belt and won't actually contact the shoulder? I wouldn't know as I don't have a headspace gauge for my 7 mag.

The rest of what you're saying I believe is what everyone is saying, he needs to make sure he is bumping the shoulders back only a tiny amount, I like to do a couple thousandths to make chambering rounds easy but not so much that it causes issues.

 

[jstamper]

then sized minimally in order not to create too much head space for future case reloading life.

+1.

You can simply adjust FL dies out to where only the neck is sized, and in fact, I've had very good results with leaving a portion at the bottom of the neck unsized.

For 7mag, I use a Lee Collet (neck sizing) die. I've got a body die to bump the shoulder should that become necesary, but I've never even had to take it out of the box, at least through the fourth firing.

 

[Bob Wright]

We're all talking headspace from the shoulder datum, not measuring the head to the belt.

 

[epoletna]

BigBull beat me to it -- there is a bunch of incorrect information floating around here for a belted magnum case. As BigBull said, head space in a belted magnum is measured from the bolt face to the top of the belt. The measurement from the bolt face to the shoulder datum is used for head space measurement in non-belted cases.

This is not to say OP is not pushing his shoulders back too far, just that is not a measurement of "head space."

OP should compare measurement from case head to shoulder datum to know how much he is bumping the shoulder back, and not exceed .002 for that bump. More might lead to case head separation, but that is NOT head space he's measuring on a 7mm Rem Mag.